1. Field of the Invention
The present invention relates to electric rotating machines, each comprising at least a stator and a rotor therein, such as an induction motor, a synchronous motor, a magnet motor, etc.
2. Description of Prior Art
As conventional arts in relation to the above electric rotating machines are already known, for example, Japanese Patent Laying-Open No. Sho 56-110464 (1981), Japanese Patent Laying-Open No. Hei 3-190543 (1991), and Japanese Patent Laying-Open No. Hei 4-87537 (1992).
In the Japanese Patent Laying-Open No. Sho56-110464 (1981), there is described a motor, wherein a bracket (i.e., a portion for holding the bearing) having a bearing for holding an axis of the rotor therein is held on an inner diameter portion (i.e., on an inner diameter reference surface) of the stator, thereby the axes of the above-mentioned stator and the above-mentioned rotor are combined coaxially.
Also, in the Japanese Patent Laying-Open No. Hei 3-190543 (1991), there is described a frame apparatus for the electric rotating machine, having a stator of a circular locus in the inner diameter thereof, and bearing portions for rotatably supporting an axis at a central portion thereof, which pierces through and is fixed to the rotor being positioned opposing to the interior diameter with an aperture between the inner diameter thereof.
End brackets are inserted into the inner diameter of the rotor from the both ends in the axial direction thereof, each having a fitting portion which is formed by bending at least two or more of the leg portions extending in radial directions therefrom into the axial direction of the electric rotating machine, so as to be inserted into the inner diameter thereof. The rests of the leg portions are extended into an outer diameter direction as they are, so as to form or provide projecting portions for the purpose of protection of the coil ends.
Also, in the Japanese Patent Laying-Open No. Hei 4-87537 (1992), there is described an electric rotating machine, being constructed with an E-ring and a gutter for it, which is provided in a shaft, so that, through the shaft piercing through at the center of the rotor in which are inserted windings opposing to the inner diameter side of the stator in a ring shape, two end brackets, each having a stop ring, one pre-pressure spring, and two end brackets are pushed into the inner diameter side at each open side end surface thereof, on both end surfaces of the stator in the axial direction of the shaft at a predetermined pressure. Also, a recess portion and a projection are provided, for stopping the relative movement of both in a rotation direction, on the inner diameter side of the stator and on the open side end surface of the end bracket(s).
In the fields of equipment for industrial use, of household electric appliances, and of automobiles, etc., motors which drive those equipment and appliances are required to be high in the efficiency, as well as small in size and light in the weight thereof. For satisfying such a requirement, a brushless motor begins to be applied into various fields, in which motor a rare earth high performance permanent magnet is applied as the rotor and the windings are wound in high density in the stator.
Classifying the methods for forming winding coils on the stator, they can be roughly divided into two ways, i.e., the one is a concentrated winding and the other is a distributed winding. In the concentrated winding, the coils are wound in each of magnetic pole teeth 57, as shown in FIG. 12 (a), for example. While, in the distributed winding, the coils are wound bridging over a plurality of magnetic pole teeth 57, as shown in FIG. 18.
To the concentrated winding, in general, a direct winding method is applied. With this method, on the inner diameter of the stator core, the coils are wound into the stator slots, directly by driving a nozzle through which an enamel wire passes. With this method, however since the coils are wound with being twisted from the inner periphery side of the core, it is impossible to wind the coils in alignment, and there occurs many portions where the wires intersect or cross each other. As a result of this, there is a limit for reducing the height of the coil ends.
Also, as the method for the distributed winding, an inserter method is common, in which the both sides of the coil are compulsively slid or slipped into the slots from the opening portions thereof at the same time in the direction of the outer diameter, so as to be inserted therein. However, there are still limits in the high density of the windings, and as well as in the height of the coil end.
Then, there is known a method for forming the concentrated winding with high density, for example, in Japanese Patent Laying-Open No. Hei 6-105487 (1994) or Japanese Patent Laying-Open No. Hei 6-261475 (1994), in which is shown a method of installing the coils wound on bobbins onto the divided cores. Also, as a method for forming the distributed windings with high density, in Japanese Patent Laying-Open No. Hei 9-215238 (1997), there is shown a method for reducing the height of the coil ends by forming each coil end into a predetermined shape.
Also, in a case of a motor on which is required a high load drive, Joule's heat occurring in the stator coils when being driven. Therefore a cooling construction is important for realizing such a motor with high efficiency. As a method for achieving such a cooling, there is shown a cooling method for the motor, in which a passage(s) for coolant is provided in a housing, for example, in Japanese Patent Laying-Open No. Hei 9-9561 (1997).
In the Japanese Patent Laying-Open No. Sho 56-110464 (1981) mentioned above, since the motor is constructed such that the axial length of the rotor is shorter than that of the stator, it is impossible for the rotor to effectively utilize the magnetic flux generated by the stator. Therefore it has a drawback that the torque efficiency thereof is decreased when it is small-sized.
Also, in any one of the conventional arts mentioned above, no consideration is paid for an aspect of achieving the small-sizing and the high efficiency in the electric rotating machine, by greatly improving heat radiation property of the coils thereof, nor of achieving good or superior property in disassembling with simple construction thereof.